Zacarias Moussaoui claims the Saudi Arabian royal family helped fund the Sept. 11 attacks. Audie Cornish talks to Gregory Gause, a professor of international studies at Texas A&M University.

AUDIE CORNISH, HOST:

Some new allegations today in an old conspiracy, specifically what, if any, connection do the government of Saudi Arabia have to the 9/11 terrorist attacks? People are taking note because of who and where the allegations are coming from, the supermax prison in Colorado where convicted al-Qaida member Zacarias Moussaoui is currently serving a life sentence. Some families of 9/11 victims are suing the Saudi government. And a judge in that case allowed lawyers to visit him and get testimony. Moussaoui says that his al-Qaida bosses told him to keep a database of donors who helped fund the group in the years leading up to the attack. And that list included members of the Saudi royal family. Here to help us sort out these allegations is Gregory Gause. He's the head of the International Affairs Department at the Bush School of Government at Texas A&M University. Welcome back to the program.

GREGORY GAUSE: Thank you.

CORNISH: Remind us again who Moussaoui is, his connection to 9/11.

GAUSE: Moussaoui was considered to be the 20th hijacker. There were 19 hijackers in the attacks of 9/11. And Moussaoui was supposed to be the 20th. That was the hypothesis. But he had been apprehended before the attacks. He was in jail when they occurred.

CORNISH: And the allegations he's making now - more importantly, the people he's making them about - can you give us more detail?

GAUSE: Moussaoui is charging that very top-level princes in the Saudi royal family, who had very high level positions in the Saudi government, were direct financial and political supporters of Osama bin Laden, including the Saudi ambassador to the U.S. at that time, Prince Bandar Bin Sultan and the head of the Saudi foreign intelligence agency, Prince Turki Al Faisal. He's also charging that one of the richest of the princes, Prince Alwaleed bin Talal, was also a financial supporter.

CORNISH: These are very serious allegations. How credible is he as a witness?

GAUSE: I wouldn't want to build my entire case on Moussaoui's assertions alone. This has come out so long after the attacks. It seems to me that you would need more to corroborate charges of that level of seriousness.

CORNISH: So help us understand what this means for the families of 9/11 victims who are seeking his testimony. I mean, is there other evidence? What is actually known about a potential link between the Saudi government and al-Qaida?

GAUSE: Well, we don't know much because proving a negative is very difficult. It's almost impossible to prove that someone didn't have any involvement in a particular event. I think that what we know, at least publically, is what's been released from the various investigations, not just the 9/11 commission but also congressional investigations. At least from the public release of the results of these investigations, there were no allegations that the Saudi government was directly involved.

CORNISH: And yet, this idea persists, right? I mean, this came out because of a lawsuit filed against Saudi Arabia by the relatives of people killed in 9/11. Can you talk about the context here, why this is a persistent allegation?

GAUSE: I think it's a persistent allegation because of some important facts that are indisputable. Fifteen of the 19 hijackers were Saudi Arabians. And Osama bin Laden was a Saudi Arabian. Now, bin Laden had basically broken with the Saudi government in the mid-'90s. They had revoked his citizenship. He was quite critical of them. But I think the fact that there were so many Saudis involved in this has led to the persistence of the allegation that the Saudi government must somehow have been involved.

CORNISH: Gregory Gause, what will you be watching for next in this case or with this new testimony?

GAUSE: Well, I think there's going to have to be some corroboration from an independent source, other than Moussaoui, of these kinds of charges. But up until now, despite the enormous amount of investigation, we haven't seen that other shoe drop that confirms a Saudi government role in the attacks.

CORNISH: Gregory Gause, he's a professor of international affairs at Texas A&M University at the Bush School of Government. Thank you so much for speaking with us.

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